C# can't find an entry point in Fortran dll

Question

I was given a working FORTRAN program and i have to write C# GUI for it (don't ask why). This program already has FORTRAN GUI, so i exctracted all the computing subroutines and put it into FORTRAN dll. This dll is built of 4 files: one static library, one FORTRAN77 file(.for) and two FORTRAN90 files(.f90). I've put all subroutines supposed to be called from within C# code into EXPORT.f90.
FORTRAN CODE:

MODULE MYVAR
  REAL*8 LK
  COMMON LK
END MODULE    

SUBROUTINE SETLK(NEWLK)
  !DEC$ ATTRIBUTES DLLEXPORT :: SETLK
  USE MYVAR
  REAL*8 NEWLK
  LK = NEWLK
END

SUBROUTINE GETLK(LKOUT)
  !DEC$ ATTRIBUTES DLLEXPORT :: GETLK
  USE MYVAR
  REAL*8, INTENT(OUT):: LKOUT
  LKOUT = LK
END

Now i'm trying to call them in C#

[DllImport(@"MYDLL.dll", CharSet = CharSet.Ansi,
CallingConvention = CallingConvention.Cdecl,
EntryPoint="SETLK")]
public static extern void SETLK(ref double NEWLK);

[DllImport(@"MYDLL.dll", CharSet = CharSet.Ansi,
CallingConvention = CallingConvention.Cdecl,
EntryPoint="GETLK")]
public static extern void GETLK(out double LKOUT);


static void Main(string[] args)
{
    double d1 = 1.234;
    SETLK(ref d1);
    double d2;
    GETLK(out d2);
    Console.WriteLine(d2.ToString());
}

I get EntryPointNotFoundException "Fail to find entry point 'SETLK' in 'MYDLL.dll'". What do i have to do to make it work?
Thanx

Answer 1

This thread suggests you need a .def file to declare the function exports (just as you used to in native Windows programming)